Stock saving side grip head for stretch forming machines



Sept. 15, 1964 E. w. SEAVERS 3,143,721

STOCK SAVING SIDE GRIP HEAD FOR STRETCH FORMING MACHINES Filed Aug. 17, 1960 5 Sheets-Sheet 1 INV EN TOR.

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Q A 7' TOENE K Sept. 15, 1964 E. W. SEAVERS STOCK SAVING SIDE GRIP HEAD FOR STRETCH FORMING MACHINES Filed Aug. 17, 1960 5 Sheets-Sheet 2 INVEN TOR.

Sept. 15, 1964 E. w. SEAVERS 3,148,721

STOCK SAVING SIDE GRIP HEAD FOR STRETCH FORMING MACHINES Filed Aug. 17, 1960 5 Sheets-Sheet 3 5 PRIOR Aer INV EN TOR.

401 ZU-M/ BY r 9 I 5 Armelvax United States Patent Ohio Fiied Aug. 17, 1960, Ser. No. 50,279 4 Claims. (or. 153-40 This invention relates to a stock saving side grip head for stretch forming machines, and particularly to a simple and rugged side grip head for gripping one end of a length of stock for applying endwise tension to the stock as the stock is wrapped onto the side face of a die.

For the purposes of illustration, the stretch head is described herein as applied to a stretch forming machine of the general character shown in US. Letters Patent No. 2,514,830, issued to Cyril I. Bath on July 11, 1950, its use in connection with other types of stretch forming machines being readily apparent from the illustrative example.

As disclosed in the above patent, the practice, in stretch forming lengths of metal stock about a side face die, has been to connect one end of the length of stock to a grip head on a stretch forming piston and cylinder assemblage for applying endwise tension to the stock. The grip heads heretofore employed have been arranged so that the gripped stock generally issues from the end of the head endwise of the stock. Since the heads are of considerable width transversely of the length of the stock, portions thereof extend, in a direction normal to the faces of the stock, a considerable distance outwardly from both faces. Insofar as they extend outwardly at the die side from the face of the stock which is to be applied againstthe side face ofthe die, they interfere with the approach of the trailing gripped end of the stock to the die. As the head approaches the die axially of the stock, it also approaches it laterally of the stock, and will strike the side face of the die unless a substantial length of stock is disposed between the forward end of the head and the point of instantaneous contact of the stock with the die. The distance, endwise of the stock, which the head must remain from the instantaneous point of tangency increases with the increase in radius of the side face. With a relatively flat side face, this distance can be several feet. This length of stock is wastage and adds materially to the cost of parts, especially those made of expensive alloys.

Attempts have been made heretofore to eliminate or reduce this wastage by notching the die so that the laterally extending or overhanging portions of the head at the face of the stock which is to engage the die face can fit into the notch on the die. This solution allows the forward end of the head to approach more closely to the instantaneous point of tangency at the end of the particular article being formed. However, this technique has not proven satisfactory in many instances. Further, it limits the angle through which stock can be wrapped on the die. For example, a 360 wrap cannot be obtained because of the notch in the die.

In accordance with the present invention, the objec- FIG. 1 is a top plan view of a stretch forming machine with the stretch head of the present invention connected thereto in operative condition;

FIG. 2 is an enlarged fragmentary top plan view of the stretch forming head of the present invention, and an attached portion of the machine for applying tension to the stock by way of the head;

FIGS. 3 and 4 are a front elevation and a left end elevation, respectively, of the head illustrated in FIG. 2; and 1 FIG. 5 is a series of three diagrammatic illustrations showing the advantages of the present head over the heads used in the prior art, the various conditions of operation being indicated in Sketches A, B, and C thereof, respectively.

Referring to the drawings, the present invention is shown in connection with a stretch forming machine which, as mentioned, may be that described in the above U.S. patent. The machine comprises a horizontal frame 1 on which a horizontal turntable 2 is mounted for rotation about an upright axis, the turntable being driven by suitable power means, as disclosed 'in the above identified patent. A suitable carriage 3 is mounted on the frame 1 for swinging about an upright axis 4.

Mounted on the carriage 3 is a reversible piston and cylinder assemblage 5 comprising a cylinder 6 in which a piston 7 having a rod 8 is mounted with its axis horizontal and extending toward and away from the table.

Pressure fluid is admitted to one end of the cylinder through a suitable line 9 and concurrently discharged fronithe other end through a suitable line 9a. so that pressure fluid can be supplied to the rod end of the piston and cylinder for yieldably urging the piston in the direction away from the table.

Mounted on the carriage 3 is a suitable slideway 10 which extends parallel to the axis of the assemblage 5. Slidable in the slideway 10 is a slide 11 having an upright pedestal 12. The pedestal 12 is connected to the piston rod 8 so that it can be reciprocated toward and away from the table parallel to the axis of the assemblage 5. Mounted on the pedestal 12 is a yoke 13 to which the side grip head 14 of the present invention is carried. The head 14 is connected to the yoke 13 by a pivot 15 which is generally upright so that the head can swing about an axis parallel to the axis of rotation of the table.

The head 14 is adapted to grip one end of the length of stock S for applying endwise, tension thereto as the stock is wrapped onto the side face of a die 17 by rotation of the table while the other end of the stock is gripped and held in fixed position relative to the die by a suitable clamp 18 on the die. The clamp on the die forms no part of the present invention, but is preferably one which, when it is fully seated in clamping position, has its outer peripheral face forming a continuation of a side face of the die so that the die'face is essentially unbrokenfor the full 360. 7 p I Referring to FIGS. 2 through 4, the head comprises generally a body 2% connected by a threaded socket portion 21 to an eyebolt 2,2 for swivelling about the axis of the pivot 15. A look nut is provided :for securing the head 14 in selected rotated positions about the axis of the eyebolt 22. If desired, the head 14 may be connected to the eyebolt to swivel about a'horizontal axis to in fixed position relative the body 20 during stretch form ing. In the formpillustrated, the jaw means includes a pairof jaws 23 and 2.4, the jaw 24- beingmounted in the head for sliding laterally of the head toward one side of the head and forwardly of the head, concurrently. A cam surface 24a cooperates with the jaw 24 for causing it to grip the end portion S of a length of stock in clamping engagement when it is moved toward the one side of the head. The jaw 24 is operated by a rod 26 of the piston 27 operable in the cylinder 28 to which hydraulic fluid may be supplied for advancing and retract-ing the piston, all under the control of a suitable reversing valve in a well known manner.

The jaw means are so arranged that the end portion S of the length of stock S, when gripped by them, is held in a position such that, endwise, it extends transversely of the head 14 through said one side of the head which faces toward the die face. The intermediate portion of the stock S which portion extends from the gripped end portion to the instantaneous line of tangency of the stock and die, intersects the portion S at an abrupt angle :1, as shown in FIG. 2. This angle preferably does not exceed 90, measured from the forward end of the head 14. The intersection, indicated at 25, of the end portion S and the intermediate portion S of the stock is at the side of the head, not the forward end of the head as in the prior art.

Thus, all of the portions of the stock S to be wrapped on the die are at one side of the head, and all of the head, for a material distance in each direction endwise of the stock from the intersection 25 is at that side of the stock which is outboard from the die face. As a result, as the stock is wrapped onto the die, it can be wrapped thereon until the line of intersection 25 becomes coincidentwith the line of instantaneous contact of the stock and die, or passes therebeyond, without any interference of the gripping head 14 and the die.

Generally, it is preferred that the line of tensioning force applied to the portion of the stock S at any time not only passes through the intersection 25, but also intersects the axis of the pivot 15 and extends along the axis of the trunnion 21. Thus any force applied by the pivot 15 to the head 14 for tensioning the stock endwise does not tend to swing the head so that no part of the side of the head at which the stock S is disposed becomes angularly disposed to the length of the portion S of the stock S. The advantages of this particular arrangement are readily seen by a comparison of the prior heads and the present head, as illustrated in Sketches A, B, and C of FIG. 5.

Referring first to Sketch A of FIG. 5, the prior conventional head 30 of a stretch forming machine is shown. In this head, the stock is inserted from the forward end 31 of the head and gripped in the head with the portion gnipped being merely a continuation of the length of the stock and not disposed at any angle to that portion of the stock lying between the head and the die. The other end of the stock is gripped by a suitable clamp 32 for rotation with a side face die 33. Accordingly, as the head 30 approaches the die 33, since it extends to the inboard side of the stock an appreciable distance and must necessarily do so because of the massiveness of the head, the head 30 cannot approach closely to the line of instantaneous tangency 34 of the stock and die. 7

If the stock is to be wrapped entirely around the die so as to form a 360 article, or even partially around the die, a length of stock, as indicated at a, must remain unused between the forward end of the head 30 and the point of tangency 34. Actually, a somewhat longer length of stock is lost because of the difiiculty of bringing the head quite so close to the die without danger of its swinging against, and marring the stock already wrapped on the die, or marring the face of the die.

Referring next to Sketch B, one solution of this problem is that in which the head 35, similar to the head 39, likewise extends to .the inboard side of the stock. One end of the length of stock is gripped by a suitable clamp 36 for rotation with the die 37. A suitable notch 38 is cut in the die so that the head 35 can move up closer to the instantaneous line of tangency 39. It is apparent that with this arrangement there is a limitation on the type of article that can the formed. For example, for accommodating the head, about 30 of the side face of the die cannot be used. Furthermore, since it is not safe to allow the head 35 to jam against the die, a certain length of stock a must be left unused between the forward end of the head 35 and the wall 40 of the notch 38 and thus be wasted.

Referring next to Sketch C, which illustrates the present invention, one end of the stock is clamped in fixed position tothe die 1'7 by means of a clamp 18. The outer surface of the clamp 18 is such that when it is in clamping position, its surface forms a continuation of the peripheral side face of the die 17. In this relation, it is apparent that the intersection 25 can itself become coincident with the line of tangency 41 of the stock portion S and the side face of the die 17, so that there is no loss whatever in stock between the point at which the stock issues from the head 14 and the instantaneous line of tangency of the stock with the die.

Furthermore, no notching of the die is necessary. Instead, the side of the head from which the stock extends becomes tangent to the die at the instantaneous line of tangency 41 so that the entire length of stock entirely to the point of intersection with the head can be wrapped onto the die.

7 In each of the heads 30 and 35 the pull on the stock is directly endwise of the gripped portion. Consequently,

a larger and longer portion of the stock must be gripped between the jaws of the head in order to develop sufi'icient gripping pressure to prevent slippage. With the head of the present invention, as illustrated in Sketch C, the

short end portion of the stock gripped by the head extends h' ansversely of the head and at substantially a right angle to the length of stock to be Wrapped on the die. Accordingly, the tensioning force is transversely of the gripped portion and less gripping area is necessary because of the angular-ity between the part of the stock gripped and the part wrapped.

Having thus described my invention, I claim:

1. In a stretch forming machine, a table, a side face die mounted thereon, a stretch forming assemblage, power means to effect relative rotation of the assemblage and die about a predetermined axis, means for securing one end portion of a length of stock in fixed position relative to the die, a gripping head connected to the assemblage and operable to grip the other end portion of the stock for tensioning the stock endwise and for holding 'it tangent to the side face at its instantaneous line of transversely of the head so that said intersection can itself become the instantaneous line of contact, free from interference of the head with the stock and die face, pivot means connecting the head to the assemblage for swinging of the head about an axis parallel to said predetermined axis, the line of tensioning force applied by the head endwise of the stock passing through said axis of the pivot means and said intersection, and said other end portion of the stock gripped by the head, said side of the head for a material distance in each direction endwise of the stock from said intersection of said other end portion of the stock, both lying, in their entirety, alongside said line of force at the side of said line of force which is outboard from the die face in all swung positions of the head about said axis of said pivot means. 2. The machine according to claim 1 wherein the head is connected to the pivot means for swivelling to different adjusted positions about an axis normal to, and intersecting, said pivotal axis of the pivot means, and said swivelling axis lies along said one side of the head and is substantially coincident with said line of force.

3. The machine according to claim 1, wherein the side face of the die extends 360 about an axis parallel to said predetermined axis, the means for securing said one end portion of the stock in fixed position relative to the die is disposed inwardly of the die from the side face and grips said one end portion inwardly from the side face so that the said intermediate portion of the stock adjacent said gripped one end lies on the side face and can be overlapped upon wrapping of the stock 360 about the die, whereby the tensioned stock can be wrapped progressively on the side face of the die and the line of intersection of said other end portion of the stock with said side face of the head can become substantially coincident with the instantaneous line of contact of the stock with the die and with the instantaneous line of contact of the intermediate portion With the die face adjacent with said one end when the stock is wrapped 360 about the die.

4. A stretch forming gripping head for a stretch forming machine employing a side face die about which a length of stock is to be wrapped while tension is applied endwise of the stock from one end by the gripping head, said head comprising a body, jaw means carried by the body and operable to grip an end portion of a length of stock and hold said end portion so that it extends, endwise of the stock, transversely of the head through one side of the head, and so that an intermediate portion of the stock can extend endwise of the stock from the die and generally endwise of the head and intersect said end portion at an abrupt angle at said one side of the head, and said head, for a substantial distance endwise of the intermediate portion of the stock in each direction, being disposed wholly at the face of said intermediate portion of the stock which is to be disposed outboard from the die face, pivot means connected to the head and adapted for connecting the head to a tension assembly for swinging transversely of the stock about the pivot axis for applying stretch forming tensioning force endwise of the intermediate portion, and the pivot means being so positioned that the line of tension force intersects said intersection and the axis of the pivot means.

References Cited in the file of this patent UNITED STATES PATENTS 2,332,926 May et al. Oct. 26, 1943 2,378,482 Jager June 19, 1945 2,395,831 Jager Mar. 5, 1946 ,8 1 Bath July 11, 1950 2,849,048 Curtner Aug. 26, 1958 

1. IN A STRETCH FORMING MACHINE, A TABLE, A SIDE FACE DIE MOUNTED THEREON, A STRETCH FORMING ASSEMBLAGE, POWER MEANS TO EFFECT RELATIVE ROTATION OF THE ASSEMBLAGE AND DIE ABOUT A PREDETERMINED AXIS, MEANS FOR SECURING ONE END PORTION OF A LENGTH OF STOCK IN FIXED POSITION RELATIVE TO THE DIE, A GRIPPING HEAD CONNECTED TO THE ASSEMBLAGE AND OPERABLE TO GRIP THE OTHER END PORTION OF THE STOCK FOR TENSIONING THE STOCK ENDWISE AND FOR HOLDING IT TANGENT TO THE SIDE FACE AT ITS INSTANTANEOUS LINE OF CONTACT WITH THE SIDE FACE DURING SAID RELATIVE ROTATION, SAID HEAD INCLUDING GRIPPING MEANS OPERABLE TO GRIP SAID OTHER END PORTION AND HOLD IT SO THAT IT EXTENDS TRANSVERSELY OF THE HEAD AND INTERSECTS THE INTERMEDIATE PORTION OF THE STOCK AT ONE SIDE OF THE HEAD, WHICH INTERMEDIATE PORTION IS BETWEEN SAID INSTANTANEOUS LINE OF CONTACT AND HEAD, AT AN ABRUPT ANGLE AT SAID ONE SIDE OF THE HEAD, AND SAID ONE SIDE OF THE HEAD BEING POSITIONED TRANSVERSELY OF THE HEAD SO THAT SAID INTERSECTION CAN ITSELF BECOME THE INSTANTANEOUS LINE OF CONTACT, FREE FROM INTERFERENCE OF THE HEAD WITH THE STOCK AND DIE FACE, PIVOT MEANS CONNECTING THE HEAD TO THE ASSEMBLAGE FOR SWINGING OF THE HEAD ABOUT AN AXIS PARALLEL TO SAID PREDETERMINED AXIS, THE LINE OF TENSIONING FORCE APPLIED BY THE HEAD ENDWISE OF THE STOCK PASSING THROUGH SAID AXIS OF THE PIVOT MEANS AND SAID INTERSECTION, AND SAID OTHER END PORTION OF THE STOCK GRIPPED BY THE HEAD, SAID SIDE OF THE HEAD FOR A MATERIAL DISTANCE IN EACH DIRECTION ENDWISE OF THE STOCK FROM SAID INTERSECTION OF SAID OTHER END PORTION OF THE STOCK, BOTH LYING, IN THEIR ENTIRETY, ALONGSIDE SAID LINE OF FORCE AT THE SIDE OF SAID LINE OF FORCE WHICH IS OUTBOARD FROM THE DIE FACE IN ALL SWUNG POSITIONS OF THE HEAD ABOUT SAID AXIS OF SAID PIVOT MEANS. 